ADF&G predicting another big year for Bristol Bay sockeye
Just in time for the Pacific Marine Expo, the state's 2018 Bristol Bay sockeye forecast is out, and it's another big one. The Alaska Department of Fish and Game is predicting a total run of 51.3 million sockeye, allowing for a harvest of 38.8 million and 12.5 million counted as escapement to the spawning grounds.
"It is a big one," agreed Greg Buck, ADF&G's area research biologist for Bristol Bay. "That's 18 percent over the recent 10-year average, and 41 percent more than the long-term mean."
Most interesting is the enormous, record-shattering forecast to the Nushagak District, which just had it's all-time highest return in 2017 (19.5 million). Buck's numbers suggest a whopping 21.8 million sockeye are bound for the Nushagak District, with a pretty much unheard of 12.3 million Wood River return. The Nushagak forecast is 7.3 million, and the Igushik is 2.1 million, both uniquely large also.
The Nushagak District forecast is definitely the outsized component of the total 2018 run size.
"I don't think I have to tell anybody that we've had a couple of spectacular, at least one pretty robust brood year in the Nushagak in 2013. It showed up as the Wood River 1.2s last year and really blew it out. And that same brood year is going to be showing up as 1.3s in the Nushagak next year, and that's really the big question is whether that 2013 brood year will continue to perform as well as it has," said Buck.
"Obviously it produced record runs in the Wood and Nush [in 2017], but there's a non-trivial chance that we could beat that record next year. We are essentially off the map with these 2013 brood year returns," he said.
ADF&G west side area management biologist Tim Sands was pretty excited for the big numbers predicted for the Nushagak. Why is the west side producing these huge returns (at least predicted to) all of a sudden?
"My gut feeling is that it has to do with those recent warm winters," said Sands.
He said the warm conditions extended the growing season, improving conditions for the baby salmon.
"Early ice-out, late ice-in, especially in those Nuyakuk River lakes, the Tikchiks, it made a difference more to them because they were in a more marginal environment. Having extra growing time in those higher, upper lakes made those fish healthier, bigger, and more competitive when they got to the ocean," he said.
Sands recently reported that genetics collected in-season from harvested sockeye showed some two-thirds of the 2017 return to the Nushagak River were Nuyakuk tributary fish that had reared in the Tikchik Lakes. He believes the mild winters and quick springs gave those fish higher survivability rates.
"And you're really not talking about that much of a difference. You know, a percentage here or a percentage there and you get a big change in the number of fish coming back."
Fish and Game admits that forecasting sockeye returns is hardly an exact science, and staff are constantly debating the variables and tweaking the method.
"Forecasting future salmon returns is inherently difficult and uncertain," Buck wrote in Tuesday's publication. "We have used similar methods since 2001 to produce the Bristol Bay sockeye salmon forecast, which have performed well when applied to Bristol Bay as a whole. Since 2001, our forecasts have, on average, under-forecasted the run by 11 percent and have ranged from 44 percent below actual run in 2014 to 19 percent above actual run in 2011. Forecasted harvests have had a mean absolute percent error of 14 percent since 2001."
A few of the biologists on the state's payroll, and at least one who isn't, believe the Nushagak may actually produce a bigger run next season than officially predicted. Perhaps six or 10 million fish bigger.